1. Field of the Invention
The present invention relates to a composite diffuser structure and a backlight module. In particular, the present invention relates to a composite diffuser structure and a backlight module which can increase both of the brightness and the view angle.
2. Description of Related Art
Generally, a light beam is outputted form a light source and is emitted via a diffuser. However, the direction of the light beam emitted from the diffuser become worse. Therefore, a prism is used for modifying the direction of the light beam. The principle is to focus the light beam and increase the front brightness by utilizing the light refraction and the light reflection to improve the efficiency of the light beam emitted from the diffuser. However, by using this way, the backlight source is over-focused so that the view angle of the display screen is restricted. This means that users need to observe frames of the display screen within limited viewing angles, otherwise, the frames displayed by the display screen can not be observed clearly. Consequently, it is inconvenient for users.
Reference is made to FIG. 1A. By using the plurality of rectangular reflection structures 12a that protrudes downwards and the lenticular structure 11a, two effects are achieved. Firstly, when the incident light L1a is emitted to the structure, the incident light L1a is directly reflected by the rectangular reflection structures 12a that protrude downwards and is returned back to the light source. Secondly, when the incident light L2a is emitted to the structure, the incident light L2a is refracted by the lenticular structure 11a to generate a projection light that is upward. Therefore, the brightness of the front view angle is increased.
Reference is made to FIG. 1B, which shows the coordinate diagram of the view angle (degree) and the light illumination (a.u.) by using the lenticular structure 11a in conjunction with the plurality of rectangular reflection structures 12a that protrudes downwards. Two curves are displayed.
(1) The simulation parameters of the curve A are: the plurality of rectangular reflection structures 12a that protrudes downwards is used, wherein the opening rate thereof (the second width Ba is 1/2.5 first width Aa) is 0.4, and the thickness of the lenticular structure 11a is 128 μm calculated from the wave trough.
(2) The simulation parameters of the curve B are: the plurality of rectangular reflection structures 12a that protrudes downwards is used, wherein the opening rate thereof (the second width Ba is 1/3 first width Aa) is 0.3, and the thickness of the lenticular structure 11a is 128 μm calculated from the wave trough.
However, from the above curves, by using the plurality of rectangular reflection structures 12a that protrudes downwards and the lenticular structure 11a, the brightness of the front view angle is still inadequate.